1. Technical Field
The present invention relates to an optical module with a body portion of a box shape.
2. Related Prior Art
Conventionally, optical modules are known which have a butterfly-type package disclosed in Japanese Patent Application Laid-Open No. 2001-060635A, No. 2001-156194A, or No. H08-316503A. A general form of the, conventional optical module is as shown in FIG. 10, in which lead pins (not shown) extend from the left and right side walls of a box package 153 and an aperture 155 for connection with an optical alignment member, a lens, an isolator, or the like is formed in the front wall of the package. A semiconductor laser diode (denoted by LD) 159 is mounted on a base 152 inside the package, or on a thermoelectric cooler disposed on the base 152. Light emitted from the LD passes through a window 157 closing the aperture 155, to reach the optical alignment member 160, and then travels to an optical fiber (not shown) through a sleeve provided on the front end of the optical alignment member 160.
In this optical module, it is necessary to install the optically transparent member 157 such as a sapphire plate in the window 155 to transmit the light from the LD, in order for hermetic sealing of the package. For optically coupling the optical fiber with the LD 159, it is typical to arrange two lenses, a first lens 158 between the LD 159 and the window in the package, and a second lens (not shown) between the window and the optical alignment member 160 outside the package. More specifically, the first lens 158 converts the light from the LD 159 into a nearly parallel beam and thereafter the second lens focuses this parallel beam on a central region of an end surface of a stub 161 which is a part of the optical alignment member 160. Since the mounting position of the LD 159 is set apart from the end surface of the stub 161, it is forced to adopt such a 2-lens system. This configuration results in increasing the number of the components and the complexity of the structure and, in turn, raising the cost of the optical module 151.
An object of the present invention is therefore to provide an optical module able to suppress the increase in the number of the components and the complexity of the structure.